The program sponsors experimental research in terrestrial ecosystems in North America. Most of the research is in natural (rather than managed) ecosystems. Some of the research is in situ experimentation, and some of the research uses "constructed" ecosystems (i.e., ecosystems constructed for the purpose of research). Both whole-ecosystem experiments and process-level studies are supported.

Part of the program's FACE experiment in Wisconsin.

The program is the principal sponsor of the world's largest long-term study of ecological effects of changes in atmospheric composition associated with energy production (i.e., the Rhinelander, Wisconsin, FACE [free-air CO2 enrichment] experiment). The Rhinelander FACE study began fumigating northern hardwood forest stands, in the field, with elevated concentrations of both carbon dioxide and ozone in 1998. The program also sponsored the largest long-term study of effects of altered precipitation amount on ecosystem structure and functioning (i.e., the Throughfall Displacement Experiment [TDE] at the Oak Ridge National Laboratory [ORNL] in Tennessee). The TDE was conducted from 1993 through 2007.

In addition to large-scale field manipulations of climatic factors and atmospheric composition, the program also sponsors mesocosm research in controlled-environment laboratory, glasshouse, and field chambers to facilitate critical ecosystem research in a cost-effective and time-efficient manner. Moreover, the program supports mathematical modeling and data and information synthesis activities. It does this as both components of experimental research projects and as stand-alone modeling and synthesis projects.

The final component of the program is the long-term monitoring and analysis of ecosystem structure and functioning on the Walker Branch Watershed at ORNL. This monitorig and analysis is meant to improve understanding of any ecological effects of climatic variability and change during recent decades.